In general, an anisotropic conductive films (ACF) containing conductive particles is widely used when an electronic component such as an integrated circuit is mounted on a substrate in COG (Chip on Glass) connection for connecting an integrated circuit directly to a glass substrate such as a liquid-crystal display or FOG (Film on Glass) connection for connecting a flexible printed board to a glass substrate of a flat panel display. The anisotropic conductive film is a thermosetting resin film with fine conductive particles dispersed therein. By interposing the anisotropic conductive film between aligned electrodes and performing thermal compression, the conductive particles positioned between the electrodes can form a conductive route. On the other hand, insulation properties of the thermosetting resin can reduce a short circuit between electrodes adjacent in a substrate surface direction. That is, the anisotropic conductive film has anisotropy of forming conductivity in a pressurizing direction (direction of both of the electrodes) and insulation properties are kept in a non-pressurizing direction (surface direction of the substrate). Having these characteristic, the anisotropic conductive film can collectively connect a plurality of electrodes provided on an integrated circuit, printed board, glass substrate, or the like, and can retain insulation properties of adjacent electrodes in the substrate surface direction.
However, with high fineness and high density of connection circuits in electronic devices in recent years, reliability of connection using the anisotropic conductive film matters. That is, when the size of an electrode as a connection target decreases, the number of conductive particles contributing to conductivity between paired electrodes decreases, and connection reliability between the electrodes may not be sufficiently obtained. Moreover, when a space between electrodes adjacent in the substrate surface direction is narrowed, both of the adjacent electrodes and the conductive particles may be in contact with each other, and insulation reliability may not be sufficiently obtained. Thus, for example, an anisotropic conductive film in a state with conductive particles dispersed by means such as application of a magnetic field and as being separated from other conductive particles is disclosed (for example, refer to Japanese Unexamined Patent Application Publication No. 2015-167106).